1. Field
The present invention relates to a lithographic apparatus and a method for manufacturing a device.
2. Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of flat panel displays, integrated circuits (ICs) and other devices involving fine structures. In a conventional apparatus, a patterning device, which may be referred to as a mask or a reticle, may be used to generate a circuit pattern corresponding to an individual layer of a flat panel display (or device). This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on a substrate (e.g. a glass plate). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.
Instead of a circuit pattern, the patterning means may be used to generate other patterns, for example a color filter pattern, or a matrix of dots. Instead of a mask, the patterning device may comprise a patterning array that comprises an array of individually controllable elements. An advantage of such a system compared to a mask-based system is that the pattern can be changed more quickly and for less cost.
In general, a flat panel display substrate is rectangular in shape. Known lithographic apparatus designed to expose a substrate of this type typically provide an exposure region which covers a full width of the rectangular substrate, or which covers a portion of the width (for example half of the width). The substrate is scanned underneath the exposure region, whilst the mask or reticle is synchronously scanned through the projection beam. In this way, the pattern is transferred to the substrate. If the exposure region covers the full width of the substrate then exposure is completed with a single scan. If the exposure region covers, for example, half of the width of the substrate, then the substrate is moved transversely after the first scan, and a second scan is performed to expose the remainder of the substrate.
Another way of imaging includes pixel grid imaging, in which a pattern is realized by successive exposure of spots.
Typically, substrate support devices that support a substrate during patterning are sized to hold one substrate. This is true as substrates have become larger and larger, for example, in the formation of flat panel displays. However, when smaller substrates are sometimes used on these large support devices, only one is exposed at a time even. This reduces throughput and makes the systems inefficient.
Therefore, what is needed is a system and method that allow for increased throughput in a lithography system.